Fig. 1.

Comparison between short-day versus long-day photoperiod reveals changes in Hdac gene expression in the hypothalamus. (A) As positive controls, hypothalamic expression of Dio2 increased and Dio3 decreased in long-day conditions relative to short-day. (B) A reporter of thyroid hormone signaling (Nrgn) did not change between short- and long-day while a reporter of retinoic acid signaling (Rarb) significantly increased in long-day conditions but no such change was seen for other members of the RAR family, Rara or Rarg. (C) Three HDAC genes, Hdac4, 6 and 9 showed significantly higher expression in long-day photoperiod, although the change in Hdac9 was small. (D) In situ hybridization verified the increase in expression of Hdac4 predominantly in the ependymal layer around the third ventricle (3V). (E) Quantification of in situ hybridization in the ependymal layer shows a significant five-fold increase in Hdac4 expression in long-day photoperiod. qPCR quantification of gene expression is shown relative to Actb levels. ^∗p < 0.05, ^∗∗∗p < 0.001.